From 7a373f6683afb799c8387bdec1da6a07e9e55b33 Mon Sep 17 00:00:00 2001 From: Phil Sutter Date: Fri, 15 Nov 2019 10:47:25 +0100 Subject: nft: Fix -Z for rules with NFTA_RULE_COMPAT The special nested attribute NFTA_RULE_COMPAT holds information about any present l4proto match (given via '-p' parameter) in input. The match is contained as meta expression as well, but some xtables extensions explicitly check it's value (see e.g. xt_TPROXY). This nested attribute is input only, the information is lost after parsing (and initialization of compat extensions). So in order to feed a rule back to kernel with zeroed counters, the attribute has to be reconstructed based on the rule's expressions. Other code paths are not affected since rule_to_cs() callback will populate respective fields in struct iptables_command_state and 'add' callback (which is the inverse to rule_to_cs()) calls add_compat() in any case. Signed-off-by: Phil Sutter Reviewed-by: Florian Westphal Acked-by: Pablo Neira Ayuso --- iptables/nft.c | 39 +++++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) (limited to 'iptables') diff --git a/iptables/nft.c b/iptables/nft.c index 83cf5fb7..599c2f7e 100644 --- a/iptables/nft.c +++ b/iptables/nft.c @@ -2897,6 +2897,44 @@ const char *nft_strerror(int err) return strerror(err); } +static int recover_rule_compat(struct nftnl_rule *r) +{ + struct nftnl_expr_iter *iter; + struct nftnl_expr *e; + uint32_t reg; + int ret = -1; + + iter = nftnl_expr_iter_create(r); + if (!iter) + return -1; + +next_expr: + e = nftnl_expr_iter_next(iter); + if (!e) + goto out; + + if (strcmp("meta", nftnl_expr_get_str(e, NFTNL_EXPR_NAME)) || + nftnl_expr_get_u32(e, NFTNL_EXPR_META_KEY) != NFT_META_L4PROTO) + goto next_expr; + + reg = nftnl_expr_get_u32(e, NFTNL_EXPR_META_DREG); + + e = nftnl_expr_iter_next(iter); + if (!e) + goto out; + + if (strcmp("cmp", nftnl_expr_get_str(e, NFTNL_EXPR_NAME)) || + reg != nftnl_expr_get_u32(e, NFTNL_EXPR_CMP_SREG)) + goto next_expr; + + add_compat(r, nftnl_expr_get_u8(e, NFTNL_EXPR_CMP_DATA), + nftnl_expr_get_u32(e, NFTNL_EXPR_CMP_OP) == NFT_CMP_NEQ); + ret = 0; +out: + nftnl_expr_iter_destroy(iter); + return ret; +} + struct chain_zero_data { struct nft_handle *handle; bool verbose; @@ -2961,6 +2999,7 @@ static int __nft_chain_zero_counters(struct nftnl_chain *c, void *data) * Unset RULE_POSITION for older kernels, we want to replace * rule based on its handle only. */ + recover_rule_compat(r); nftnl_rule_unset(r, NFTNL_RULE_POSITION); if (!batch_rule_add(h, NFT_COMPAT_RULE_REPLACE, r)) { nftnl_rule_iter_destroy(iter); -- cgit v1.2.3